Apparatus and method for safely inserting an introducer needle into epidural space

ABSTRACT

An epidural needle assembly is provided, permitting the accurate introduction of a large bore introducer sleeve needle into the epidural space in the spinal column of a patient using the loss of resistance technique. The large bore introducer needle has a beveled side opening at its tip and with a tissue piercing point at the distal extension of the needle. A syringe needle is received within the introducer needle with a distal head of the syringe needle filling the beveled side opening at the distal end of the introducer needle when the syringe hub is fully seated. The lumen of the syringe needle exits the syringe needle head at the side opening of the introducer needle immediately adjacent the tissue piercing point of the introducing needle. The needle assembly may be inserted and advanced, with precise tactile feedback, into a patient, thus accurately detecting the introduction of the introducer needle into epidural space.

FIELD OF THE INVENTION

The present invention relates generally to the field of hyperdermicneedles, and more particularly to an epidural needle assembly for safelyintroducing a introducer needle into the epidural space in the spinalcolumn of a patient.

BACKGROUND OF THE INVENTION

Traditionally, actually for centuries, needle access to the epiduralspace around the spine has been achieved with a technique known as “lossof resistance”. During this technique, the operator will normally use asmall gauge (18 G to 14 G, and more typically, 18 G or 17 G) needle anda syringe of saline or air attached to the hub of the needle. The needleis advanced through the skin and underlying tissue until it engages theligament layers over the spine and epidural space. As the needle isadvanced through the soft tissue underlying the skin, the operatorexerts constant pressure on the plunger of the syringe, which isattached to the hub of the needle. When the needle is within ligament,there is considerable resistance on the plunger. However, when theneedle passes into the epidural space, the resistance is gone or lostand the plunger advances easily at this point thereby informing theoperator through tactile response that the tip of the needle has beenintroduced into the epidural space.

Physicians are trained to use typically 17 and 18 gauge needles in mostinstances. Accordingly, the tactile response with needles of this gaugeis very familiar to the operator. For best clinical practice, thisprecise tactile feedback should be maintained to optimize the chances ofproperly identifying the epidural space.

It is also common practice to introduce large bore sleeve needlesgenerally referred to as introducer needles into the epidural space forintroduction of larger elements, such as paddle, flat or wire leads,into the epidural space. For example, see U.S. Pat. Nos. 7,022,109;6,553,264; 6,309,401; 6,249,707; 6,245,044; 5,669,882 and 5,255,691.

The gauge of such introducer sleeve needles exceeds that which isfamiliar to the operator, and accordingly, use of the loss of resistancetechnique is impossible when introducing the tip of such an introducersleeve needle into the epidural space.

The gauge of such introducer sleeve needles is not always specified, andfor example, in U.S. Pat. No. 6,309,401 it is based on size of thepaddle leads to be inserted through the introducer needle, and thereforewould need to be 10 gauge or larger.

In the prior art, the method normally used to introduce such anintroducer sleeve needle into epidural space is to attach a syringe tothe large oblong introducer hub, and attempt to use the loss ofresistance technique. However, in this case, the precision of thetactile feedback from such a large bore needle is lost and this providesa significant negative impact on the success rate of the procedure forintroducing an introducer sleeve needle into the epidural space.

Other problems are also incurred. With respect to the introducer sleeveneedle disclosed in U.S. Pat. No. 6,309,401, a hub is fixed to the bodyof the introducer needle and cannot be removed. In order to pass paddleleads through the introducer sleeve needle, the leads would have to passthrough the hub at some point. The hub would either be too small to passthe paddle leads, or it would have to be as large an opening as thediameter of the oblong introducer to fit the paddle leads therethrough.In the first instance, the operator would not be able to pass the leadsthrough the device. In the latter case, the operator would never find asyringe with the proper fitting to mate with the hub to even attempt aloss of resistance technique. Furthermore, in the latter instance, therewould be a complete loss of tactile feedback to the operator as theintroducer sleeve needle is advanced making it extremely risky anddifficult to identify the epidural space.

It is a principal object of the present invention to eliminate theseaforementioned risks and shortcomings, and to provide an epidural needleassembly for safely introducing a large bore introducer sleeve needleinto the epidural space of the spinal column of a patient and forinserting wide lead elements, or multiples thereof, into the epiduralspace. The invention also uniquely provides for the simultaneousintroduction of multiples of lead elements into the epidural space orother subcutaneous tissue layer.

SUMMARY OF THE INVENTION

The present invention provides an introducer epidural needle assemblyfor safely achieving access to the epidural space, which includes anelongated large bore introducer sleeve needle having a beveled sideopening at its distal tip which provides a tissue piercing point at thedistal tip. A large diameter lumen extends fully through the introducersleeve needle. The combination further includes a syringe needle that isremovable insertable within the lumen of the introducer sleeve needleand the syringe needle is provided with a syringe hub at its proximalend and a head at its distal end. The syringe needle head is dimensionedand contoured to fill the beveled side opening at the distal end of theintroducer sleeve needle when the hub of the syringe needle is fullyseated on the proximal end of the introducer sleeve needle. The syringeneedle head thus seated provides a syringe needle lumen exit of apredetermined gauge which exits the syringe needle head immediatelyadjacent the flesh piercing point of the introducer sleeve needle. Thisepidural needle assembly uniquely permits the loss of resistancetechnique to be employed when introducing the introducer sleeve needleinto the epidural space. Such precise introduction and positioning ofthe introducer sleeve needle was not previously possible with the needleassemblies of the prior art.

The method or procedure of the present invention is carried out byfilling the beveled side opening of the introducer sleeve needle withthe head of the syringe needle by inserting the syringe needle into thelumen of the introducer sleeve needle until the hub of the syringeneedle is fully seated on the distal end of the introducer sleeveneedle. Then, the lumen exit of the syringe needle on the head of thesyringe needle is plugged by inserting a solid stylet into the lumen ofthe syringe needle to thereby block the entry of debris into the syringelumen exit, thereby completing the assembly.

Then the needle assembly is manipulated to percutaneously insert thepoint of the introducer sleeve needle into skin of the patient at adesired spinal area. Thereafter the stylet is removed from the syringeneedle lumen and a plunger actuated syringe containing non-toxic fluid,such as saline solution or air, is secured to the syringe hub of thesyringe needle. The assembly is thus further advanced through softtissue layers underlying the skin toward the epidural space whileapplying plunger ejection pressure to the syringe, thereby ejecting thenon-toxic fluid under pressure from the syringe needle lumen exitimmediately adjacent to the introducer sleeve needle point. This permitsdetecting the entry of the point of the introducer sleeve needle intothe epidural space with precise tactile feedback to the plunger of thesyringe. Thereafter the syringe needle may be removed from theintroducer needle lumen whereby the introducer sleeve needle remainspositioned in the epidural space for future use.

The syringe needle hub is keyed with the proximal end of the introducerneedle when they are fully seated to each other to prevent relativerotation. In a similar fashion, the stylet is also keyed againstrotation relative to the syringe needle when fully seated together toplug the syringe needle lumen exit.

In an alternative embodiment, the introducer sleeve needle is providedwith a longitudinal side slot that extends the full length of theintroducer sleeve needle. The syringe needle further includes alongitudinal wing rib which extends through this side slot for apredetermined lateral distance beyond the slot, whereby a tissue pathmade by the introducer sleeve needle in tissue is dilated and therebywidened for later introduction of wide lead elements through theintroducer sleeve needle and into the epidural space. Accordingly,exceptionally wide lead elements, such as paddle, flat or wire leads,may be introduced into the epidural space through the introducer sleeveneedle with portions of the wide lead protruding through the side slotof the introducer sleeve needle as the wide lead is progressing throughthe introducer sleeve needle.

The introducer sleeve needle preferably includes depth markings on theexterior surfaces thereof for assessing the depth of penetration.Typically such markings are in centimeter increments.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages appear hereinafter in the followingdescription and claims. The accompanying drawings show, for the purposeof exemplification, without limiting the scope of the invention orappended claims, certain practical embodiments of the present inventionwherein:

FIG. 1 is a view in side elevation of a large bore circular introducersleeve needle utilized in the epidural needle assembly of the presentinvention;

FIG. 2 is a view in front elevation of the introducer sleeve needleshown in FIG. 1;

FIG. 3 is a view is side elevation of a syringe needle utilized in theepidermal needle assembly of the present invention;

FIG. 4 is a view in front elevation of the syringe needle shown in FIG.3;

FIG. 5 is an exploded view of the stylet, syringe needle and introducersleeve needle shown in perspective, which are combined to provide theepidural needle assembly of the present invention;

FIG. 6 is a perspective view showing the introducer sleeve needle ofFIG. 1, 2 or 5 in combination with the syringe needle of FIG. 3, 4 or 5without the inclusion of the stylet shown in FIG. 5;

FIG. 7 is a view in side elevation showing another embodiment of anintroducer sleeve needle with an oblong bore used in the epidural needleassembly of the present invention;

FIG. 8 is a view in front elevation of the introducer sleeve needleshown in FIG. 7;

FIG. 9 is a top end view of the introducer sleeve needle shown in FIG.8;

FIG. 10 is a view in side elevation of another embodiment of a syringeneedle to be used in combination with the introducer needle embodimentshown in FIG. 7;

FIG. 11 is a view in front elevation of the syringe needle shown in FIG.10;

FIG. 12 is a view in side elevation and in vertical mid cross section ofthe introducer sleeve needle shown in FIGS. 7, 8 and 9 in combinationwith the syringe needle of FIGS. 10 and 11;

FIG. 13 is a view in front elevation of the combination shown in FIG.12;

FIG. 14 is a perspective view of the combination shown in FIG. 13;

FIG. 15 is a perspective view of another embodiment of the epiduralneedle assembly of the present invention; and

FIG. 16 is a perspective view showing the epidural needle assembly ofFIG. 15 as seen from a reverse side perspective.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 through 6, the epidural needle assembly 10 of thepresent invention is comprised, at a minimum, of the combination oflarge bore introducer sleeve needle 11 and syringe needle 12. Elongatedtubular introducer sleeve needle 11 is provided with a lumen 13extending from its distal tip 14 to its proximal end 15, with a beveledside opening 16 at its distal end. Introducer sleeve needle 11 is alsoprovided with a curved distal tip 17 having a flesh or tissue piercingpoint 18 at its distal tip.

Introducer sleeve needle 11 is a large bore needle which is provided toallow the insertion of larger objects, such as a paddle lead, flat leador a wire lead, into the epidural space after the tip 14 has beeninserted into the epidural space. All components shown are constructedof surgical stainless steel or an equivalent thereof.

Syringe needle 12 is provided at its proximal end 15 with a conventionalhub 20 for connecting a conventional plunger actuated syringe (notshown) thereto in conventional fashion. The internal lumen 21 of syringeneedle 12 is of predetermined cross section, most typically gauge 18 or17, and continuously extends through syringe needle 12. An enlarged head22 is secured to the distal end of syringe needle 12, thus it is fixedin place against rotation. Syringe needle 12 is dimensioned andcontoured to receive in lumen 13 of introducer sleeve needle 11 with thehub 20 releasably seated with the proximal end 15 of introducer sleeveneedle 11, and the head 22 filling the beveled side opening 16 when hub20 is fully seated to the proximal end 15 of introducer sleeve needle 11as illustrated in FIG. 6.

The syringe needle lumen 21 exits head 22 at the side opening 13 ofintroducer sleeve needle 11, as best illustrated in FIG. 6, immediatelyadjacent the tissue piercing tip 18 of introducer sleeve needle 11whereby the needle assembly 10 illustrated in FIG. 6 may bepercutaneously inserted and advanced with tactile feedback into apatient for thereby safely and accurately introducing the distal end 17of introducer sleeve needle 11 into epidural space. The assembly shownin FIG. 6 thus provides the ability to inform the operator as to theexact location of the point 18 and the point 23 simultaneously which isnot possible with the needle assemblies of the prior art.

The hub 20 of syringe needle 12 and the proximal end 15 of introducersleeve needle 11 are keyed against relative rotation when the hub 12 isfully seated on the proximal end 15 of introducer sleeve needle 11. Thiskeying arrangement is provided by the inter-engagement of alignmentnotch 24 provided in the bottom of hub 20 and the correspondingalignment protrusion 25. The inter-engagement of protrusion 25 intoalignment notch 24 of hub 20 is preferably a snap fit to therebymaintain the two members together in alignment, until such time thatthey are pulled apart with force.

This epidural needle assembly 10 shown in FIG. 6 thus uniquely permitsthe loss of resistance technique to be precisely employed whenintroducing the large bore introducer sleeve needle 11 into the epiduralspace.

The needle assembly 10 of the present invention may also include astylet 26 which is a solid rod that is removably insertable in thesyringe lumen 21. The stylet 26 is dimensioned to plug the syringe lumen21 where it exits head 22 whereby debris is prevented from entering thedistal end of the syringe lumen. Stylet 26 is provided with a hub 27 atits proximal end which is dimensioned and contoured to seat into syringeneedle hub 20 when stylet 26 is fully inserted into the syringe needlelumen 21 whereby lumen exit 28 in head 22 is fully plugged. Thus thedistal end 29 of stylet 26 is contoured to mate the surface of syringeneedle head 22 at the portion 30 which is exposed by the beveled sideopening 16 of introducer needle 11 when stylet 26 is fully seated intosyringe needle 12.

Stylet hub 27 and syringe needle hub 20 are keyed against relativerotation when fully seated together by alignment protrusion 31 on hub 27which projects into alignment notch 32 at the proximal end of syringehub 20. The fit between alignment protrusion 31 and complementaryalignment notch 32 is preferably that of a snap fit to preventaccidental dislodgement therebetween.

The embodiment of the epidural needle assembly 10 of the presentinvention illustrated in FIGS. 7 through 13, is in all respectsidentical to that illustrated in the previous embodiment with theexception that the cross section of introducer sleeve needle 11 in theprevious embodiment is circular, whereas the cross section of theembodiment illustrated in FIGS. 9 through 13 is oblong. Accordingly, thesame elements of this latter embodiment are designated with theidentical reference numerals.

The needle assembly of the present invention is applied by first fillingthe beveled side opening 16 of introducer sleeve needle 11 with the head22 of syringe needle 12 by inserting syringe needle 12 into the lumen 13of introducer sleeve needle 11 until hub 24 is fully seated on thedistal end 15 of introducer sleeve needle 11. Next, the lumen exit 28 ofsyringe needle lumen 21 is plugged by inserting solid stylet 26 intolumen 21 of syringe needle 12 to thereby block the entry of debris intosyringe lumen exit 21, thereby completing the assembly.

This assembly is then inserted into the skin of the patient at a desiredspinal area by percutaneously inserting the point 18 of introducersleeve needle 11, together with the remainder of the assembly into theskin. Once the skin has been penetrated, stylet 26 is removed fromsyringe needle lumen 21 and a conventional plunger actuated syringe (notshown) containing non-toxic fluid, such as saline solution or air, issecured in a conventional manner to syringe hub 20.

Then the assembly is advanced through soft tissue layers underlying theskin toward epidural space while applying plunger ejection pressure tothe syringe, thereby ejecting fluid under pressure from the syringeneedle lumen exit 28 positioned immediately adjacent to the introducerneedle tissue piercing point 18, thereby permitting the operator toaccurately detect entry of the point 18 of large bore introducer sleeveneedle 11 into epidural space with precise tactile feedback to theplunger of the syringe.

With the introducer needle tip 17 being safely introduced into theepidural space, the syringe needle 12 may then be removed from theintroducer needle lumen 13 whereby the introducer sleeve needle 11remains positioned in epidural space for future use, such as insertionof a paddle lead.

Referring next to FIGS. 15 and 16, another embodiment of the epiduralneedle assembly 10 of the present invention is illustrated. Thisembodiment is in most respects identical to that of the previousembodiments, and accordingly, like elements are designated with the samereference numerals.

In this embodiment, the elongated tubular introducer sleeve needle 11 isprovided with a longitudinal side slot 35 that extends the full lengthof introducer sleeve needle 11. Syringe needle 12 includes alongitudinal wing rib 36 which extends through side slot 35 for apredetermined lateral distance d therebeyond. Accordingly, when theneedle assembly 10 is percutaneously introduced into body tissue, thelongitudinal wing rib 36 serves to cut, dilate and widen the path of theintroducer sleeve needle 11 for later introduction of elements orequipment, such as paddle leads, flat leads or wire leads, which aremuch broader than permitted with original prior art versions of epiduralneedle assemblies or introducer sleeve needles.

The wing rib 36 is an integral part of the syringe needle 12 and thuswhen syringe needle 12 is removed from introducer sleeve needle 11, wingrib 36 is also removed as an integral part thereby leaving a widenedpath in the tissue adjacent slot 35 of introducer sleeve needle 11,which remains imbedded. Accordingly, a much wider than normal leadelement may be inserted through the introducer sleeve 11 into epiduralspace. The wide lead passes not only through the lumen of introducersleeve needle 11 but also portions thereof extending through slot 35 andthrough the dilated tissue passage produced by wing rib 36. Accordingly,introduction of much wider lead equipment or elements is permitted. Forexample, a 10 mm wide lead element may be inserted as compared to a 4 mmlead element possible with the introducer needles of the prior art, orthe simultaneous passage of multiple leads side by side.

The longitudinal wing rib 36 is contoured and specifically matched andmated to fit the length of the apparatus in FIGS. 3 and 4. In this way,the cutting edge of the longitudinal wing rib is positioned to navigatethrough ligaments (and other subcutaneous tissue) en route to theepidural space at the same exact time as the exit 28 of needle 12 istraversing through said tissue. Thus, the operator will know where thewing rib is in relation to the tubular introducer sleeve needle 11 atall times.

Finger grip wings 37 are provided on the upper end of syringe needle 22to facilitate handling. Finger grip wings 37, enlarged head 22, wing rib36 and the upper end 15 of syringe needle 12 are integrally molded oftransparent medical blue polypropylene. However, wing rib 36 ispreferably constructed of surgical stainless steel with cutting leadingand side edges to cut tissue.

Introducer sleeve needle 11 is provided with 1 cm depth markings 38 toaid the operator in accessing how deep beneath the tissue the tip 18 islocated.

I claim:
 1. An epidural needle assembly for safely introducing anintroducer needle into the epidural space in the spinal column of apatient, comprising: a elongated tubular introducer sleeve needle havinga lumen extending from its distal tip to its proximal end with a beveledside opening at its distal tip providing a tissue piercing point; asyringe needle having a proximal end and a distal end and an internallumen of predetermined cross section continuously extendingtherethrough, a syringe hub secured to said proximal end and a headsecured to said distal end; said syringe needle dimensioned andcontoured to be received in said lumen of said introducer sleeve needlewith said hub releasably seated with said proximal end of saidintroducer needle and with said head filling said beveled side openingwhen said hub is fully seated to the proximal end of said introducersleeve needle; said syringe needle lumen exiting said head at said sideopening immediately adjacent said tissue piercing tip of said introducersleeve needle whereby said needle assembly may be percutaneouslyinserted and advanced with tactile feedback into a patient for therebysafely and accurately introducing the distal end of said introducersleeve needle into epidural space.
 2. The needle assembly of claim 1,wherein said syringe lumen is in the range of gauge 18 to
 14. 3. Theneedle assembly of claim 2, including a syringe secured to said syringehub.
 4. The needle assembly of claim 1, wherein said distal tip of saidintroducer sleeve needle is curved in the direction of said beveled sideopening.
 5. The needle assembly of claim 4, wherein the cross-section ofsaid introducer sleeve needle is circular.
 6. The needle assembly ofclaim 4, wherein the cross-section of said introducer sleeve needle isoblong.
 7. The needle assembly of claim 1, wherein said hub of saidsyringe needle and said proximal end of said introducer sleeve needleare keyed against relative rotation when said hub is fully seated onsaid proximal end of said introducer sleeve needle.
 8. The needlecombination of claim 1, including a stylet removably insertable in saidsyringe lumen and dimensioned to plug said syringe lumen whereby debrisis prevented from entering the distal end of said syringe lumen.
 9. Theneedle assembly of claim 8, wherein said stylet includes a hub at itsproximal end which is dimensioned and contoured to seat into saidsyringe needle hub when said stylet is fully inserted into said syringeneedle lumen whereby the lumen exit in said head is plugged.
 10. Theneedle assembly of claim 9, wherein the distal end of said stylet whenfully seated is contoured to mate the surface of said syringe needlehead which is exposed by said introducer sleeve needle beveled sideopening.
 11. The needle assembly of claim 9, wherein said stylet hub andsaid syringe needle hub are keyed against relative rotation when fullyseated together.
 12. The needle assembly of claim 1, said introducersleeve needle having a longitudinal side slot, said syringe needleincluding a longitudinal wing rib which extends through said side slotfor a predetermined lateral distance therebeyond whereby a path made bysaid introducer sleeve needle is dilated and thereby widened for laterintroduction of wide lead elements.
 13. The needle assembly of claim 12,wherein said introducer sleeve needle and said syringe needle arestainless steel and said wing rib is a rigid metal or plastic secured tosaid syringe needle.
 14. The needle assembly of claim 13, wherein saidmetal is metal grade steel.
 15. The needle assembly of claim 1, saidintroducer sleeve needle includes depth markings on the exterior thereoffor assessing depth of penetration.
 16. The needle assembly of claim 15,wherein said depth markings are in centimeter increments.
 17. Anepidural needle assembly, comprising: an elongated tubular introducersleeve needle having a longitudinal side slot extending the full lengththereof; a syringe needle removably received in said introducer sleeveneedle and including a longitudinal wing rib which extends through saidside slot for a predetermined distance therebeyond whereby a path madeby insertion of said introducer sleeve needle in tissue is dilated bysaid wing rib and thereby widened for later introduction of a wide leadelement or other object.
 18. A method of safely introducing the distalend of an introducer sleeve needle into the epidural space of the spinalcolumn of a patient employing an introducer assembly for achievingaccess to the epidural space comprising an epidural needle assembly,including an elongated introducer sleeve needle having a beveled sideopening at its distal tip providing a tissue piercing point and a lumenextending fully therethrough, a syringe needle removable insertablewithin said lumen and having a syringe hub at its proximal end and ahead at its distal end which fills said beveled side opening when thehub is fully seated on the proximal end of the introducer sleeve needle,the head having a syringe needle lumen exit of predetermined gaugeexiting the head immediately adjacent said introducer point, comprisingthe steps of: filling said beveled side opening of said introducerneedle with the head of said syringe needle by inserting said syringeneedle into the lumen of said introducer sleeve needle until said hub isfully seated on the distal end of said introducer sleeve needle;plugging the lumen exit of said syringe needle lumen by inserting asolid stylet into the lumen of said syringe needle to thereby block theentry of debris into said syringe lumen exit, thereby completing theassembly; percutaneously inserting the point of said introducer sleeveneedle, together with the remainder of the assembly, into skin of thepatient at a desired spinal area; removing said stylet from said syringeneedle lumen; securing a plunger actuated syringe containing non-toxicfluid to the syringe hub of said syringe needle; advancing the assemblythrough soft tissue layers underlying the skin toward epidural spacewhile applying plunger ejection pressure to the syringe and therebyejecting said fluid under pressure from said syringe needle lumen exitimmediately adjacent to said introducer sleeve needle point anddetecting entry of the point of said introducer sleeve needle intoepidural space with tactile feedback to the plunger of said syringe; andthereafter removing said syringe needle from the introducer sleeveneedle lumen whereby the distal tip of said introducer sleeve needleremains positioned in epidural space for future use of said introducersleeve needle.
 19. The method of claim 18, keying said syringe needlehub with the proximal end of said introducer sleeve needle when fullyseated to each other to prevent relative rotation.
 20. The method ofclaim 19, keying said stylet against rotation relative to said syringeneedle when fully seated together to plug said syringe needle lumenexit.
 21. The method of claim 17, said introducer sleeve needleincluding a longitudinal side slot and said syringe needle including alongitudinal wing rib which is contoured and dimensioned to extendthrough and laterally beyond said side slot for a predetermineddistance, the step of percutaneously inserting includes insertion ofsaid wing rib for thereby dilating the insertion path made by saidassembly to provide a widened introducer path, and after removing saidsyringe needle together with said wing rib, advancing a wide leadelement through said introducer sleeve needle with portions thereofextending through said side slot.